溶劑對有機染料吸收性質的影響

Solvent Dependent Absorption Properties Of Organic Dyes

李洛忻(Luo-Xin Li)

指導教授 ： 魏台輝

國立中正大學/工學院/光機電整合工程研究所/碩士(2012年)

摘要

本論文分兩部分。在第一部份中，我們以個別的16 picosecond (ps)脈衝為光源，利用Z-scan技術調查(i)六種單一透明液體(methanol、ethanol、H2O、CS2、toluene以及THF)、以及(ii)兩種混合透明液體(methanol-ethanol以及ethanol-CS2)的非線性折射性質，目的在於探討不同種類分子混合後是否會因其間作用力而產生新的非線性折射效應。在ps時域，可能的新機制仍屬於克爾效應(Kerr effect)。在第二部份中，我們分別以個別16 ps脈衝以及16 ps脈衝串(相鄰兩脈衝間的時距為7 nanosecond (ns)，而整個脈衝串的時寬約為21 ns)為光源，調查(i)六種單一溶劑的有機溶液(SiNc/toluene、SiNc/THF、Rose Bengal/H2O、Rose Bengal/ethanol、Methyl Red/ethanol、Methyl Red/CS2)、以及(ii)三種雙溶劑有機溶液(SiNc/toluene-THF、Rose Bengal/H2O-ethanol、Methyl Red/ethanol-CS2)的非線性吸收與折射性質，目的有二：(i)探討不同溶劑是否對溶質的非線性吸收與折射性質有所影響、以及(ii)不同種類溶劑分子混合後是否會因其間作用力而產生新的非線性折射效應。當然，在ps時域，可能的新機制仍反映於溶質的基態和激發態吸收以及溶劑的克爾效應；在ns時域，可能的新機制則另外包括溶液的熱效應。
透過第一部份研究，我們在兩種混合透明液體中都未發現新的非線性折射效應。透過第二部份研究，我們在六種單一溶劑有機溶液中僅發現SiNc的吸收或折射性質不受溶劑(toluene與THF)的影響，而Rose Bengal與Methyl Red的吸收或折射性質卻都受溶劑(前者的溶劑是H2O與ethanol而後者的溶劑則是ethanol與CS2)的影響，針對此實驗結果，我們歸因為溶質與溶劑間的氫鍵影響；另方面，我們在三種雙溶劑有機溶液中發現SiNc/toluene-THF並無新的非線性吸收與折射效應，而Rose Bengal/H2O-ethanol與Methyl Red /ethanol-CS2則有新的非線性吸收與折射效應。針對混合溶劑對溶質的非線性吸收與折射性質影響，我們也歸因為溶劑與溶質間的氫鍵影響。

關鍵字

脈衝串 ； 皮秒 ； 玫瑰紅 ； 甲基红 ； 吸收 ； Z掃描

並列摘要

This thesis is divided into two parts. In the first part, we used the Z-scan technique with individual 16 picosecond (16 ps) laser pulse to investigate nonlinear refraction properties of (i) six individual transparent liquids (methanol, ethanol, H2O, CS2, toluene and THF) and (ii) two binary transparent liquids (methanol-ethanol and ethanol-CS2). The purpose of this study is to verify whether the interaction between the component liquids renders additional nonlinear refraction behaving as the well characterized Kerr effect.
In the second part of this thesis, we used the same techniques, with both individual 16 ps laser pulses and trains of 11 16 ps pulses separated by 7 nanosecond (ns) and extending over 21ns, to investigate nonlinear absorption and refraction properties of (i) six combinations of three organic dyes and five single solvents (SiNc/ toluene, SiNc/THF, Rose Bengal/H2O, Rose Bengal/ethanol, Methyl Red/ ethanol and Methyl Red/CS2) and (ii) three combinations of three organic dyes and three binary solvents (SiNc/toluene-THF, Rose Bengal/ H2O-ethanol, Methyl Red/ethanol-CS2). The first purpose of this part of study is to verify if different single solvents affect nonlinear absorption and refractive properties of the solutes. The second purpose is to clarify if the interaction between the binary solvents induces new nonlinear absorption and refraction of these solutions. It is plausible that interaction between component solvents may introduce sequential one-photon excitation of the dye molecules and Kerr effect of the solvents in the ps regime. In addition, it may results in thermal effect in the ns regime.
Via the first part of this study, we do not observe in the mixed transparent liquids additional nonlinear refraction induced by the interaction between the component transparent liquids. Via the second part of this study, we find, among the six combinations of organic dyes and single solvents, that Rose Bengal and Methyl Red show solvent dependent absorption and refraction; however, SiNc shows solvent independent nonlinear absorption and refraction. We attribute these solvent dependent nonlinear absorption and refraction to hydrogen bonds between solvents and solutes (organic dyes). Regarding the three combinations of organic dyes and binary liquids, we find that SiNc/toluene-THF does not show additional nonlinear absorption and refraction compared to SiNc/toluene and SiNc/THF. However, Rose Bengal/ H2O-ethanol, compared to Rose Bengal/H2O and Rose Bengal/ethanol as well as Methyl Red/ethanol-CS2, compared to Methyl Red/ethanol and Methyl Red/CS2, exhibit new nonlinear absorption and refraction. Regarding the three combinations of dye molecules and binary solvents, we also attribute the additional nonlinear absorption and refraction to hydrogen bonds between solvents and solutes (organic dyes).

並列關鍵字

Pico-second ； SiNc ； Methyl Red ； Rose bengal ； absorption ； Z-Scan ； pulse train

參考文獻

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